Knock Knock
by Grapenillacupcake
Summary: Sans is always napping once he arrives at his usual spot at Waterfall, so rarely does he get to take in the scenery. But, he is absolutely, one hundred percent sure, completely certain, that there was never a generic gray door on the wall. ((Some Undertale spoilers are inside this fic, so be careful!))


Knock Knock.

/

Sans is always napping once he arrives at his usual spot at Waterfall, so rarely does he get to take in the scenery.

But, he is absolutely, one hundred percent sure, completely certain, that there was never a generic gray door on the wall.

Context:

Sans, for all of his easy napping during the day, he finds it hard to go to bed at night. He grows restless, mind preoccupied heavily with thoughts he just can't halt, no matter how much he hates them. And on nights where they get particularly bad, and start to drift to times he tries his hardest to forget, he takes a night walk.

Sometimes, it's just to the closed store of Grillby's and back.

Or like this night, it was all the way to Waterfall. All the monsters were asleep, only the sounds of rushing water and distant, repeated conversations keeping him company. On the flowers with no real importance to them, he says a few bad pun-based jokes. He snickers at them before continuing on his way.

The air is wet and cold, and while it doesn't seep into his jacket easily, it does for his exposed leg bones and into his shorts. He lets out a sigh, still never breaking his grin, and he sees his own breath.

Sans keeps on walking. Familiar scenery, familiar noises, and yet on nights like this, it felt like he was exploring it all over again.

He reached the room where there was a pink, shining gem in a block of cheese, and paid it no mind. He walked to the right, but then paused.

"...Huh?" he said out loud, eyebrows furrowing in confusion. Yes, he tended to nap during his shifts, but surely he wouldn't forget a grey-door. I mean, would he waste that many potential knock-knock jokes by forgetting the door? Never.

As he steps a little closer to the door, he is suddenly struck is awareness.

Even when the truth should stay hidden from him, the great Sans, he can still figure out the truth. His mind, sensitive to the details and secrets of timelines of past and future and present, can suddenly unlock them on either accident or on purpose. It's been great to figure out what the kid was going to do this time, if there was a way to convince Papyrus this time to not go, of who else was going to fall and how far they would get to freedom before being denied of it by an undead child playing god...

but.

He is suddenly aware of what is behind the door.

He could be wrong.

He hopes with all of his being, he is not wrong. And yet, he feels fearful to hope, in the event he is wrong and there is nothing behind but despair and disappointment.

Sans is sweating, slowly lifting a shaky hand up to the doorknob. His pupils are extremely tiny, and they shake to with nervousness, with utter fear and faint excitement, anticipation, and happiness.

He grabs the doorknob. It's real.

He twists the doorknob. It's unlocked.

He walks in and closes the door behind him, and looks forward.

The door opens to a extremely short hallway that leads up to an equally small, equally gray room. In the room, is a hunched over figure, wearing a long, black cloak with long sleeves. His face is pure white, with misshapen, black eyes with white pupils. The left one is a perfect circle, and the right one is a tiny dot. There is one crack over the right and a little under it, and the second crack stops at the top of his left hands are at the front of his body, and on his face is a wide, shaky smile, black as his own clothes.

Sans collapses onto his knees, staring at his father in complete shock.

W.D. Gaster.

 _((SANS...))_

The familiar voice makes Sans cry. Tears develop in his eyes and they freely roll down his chubby skull. Heavier ones, thicker ones, appear in Gaster's eyes, and they drip to the floor as he opens his arms wide.

 _"I MISSED YOU SO MUCH."_

The smile on Gaster's face looks and feels real now, and he runs over to Sans, before suddenly stopping, just a few inches away. Sans looks at him, breath hitching, and lets out a sob. Gaster lets his arms slowly drop to his side, as if he realized something, and his fists clench. But then, he extends his arm out to his son, palm facing up.

Sans let's out a sob and quickly reaches for his father's hand, his hand facing downwards to properly meet it.

But as his hand is just inches away from touching Gaster's, his father's arm warps and wiggles before melting.

"G-" Sans says as Gaster begins to melt, but the very next second, his form simply fades away in a second, not giving either enough time to react to the sudden, unwanted departure.

There is no sign of Gaster in the room. No dust. No marks or noises or saved words. Just like before.

Sans is aware that the second he leaves the room, it'll be gone to. And he knows he has to leave the room.

But not right now.

And so, Sans weeps and weeps as heavily as he can, shaking from the force of his sobs.

All alone.

/

((This was inspired by this AMAZING comic, which I'll link here: post/130583027594/just-a-doodle-cause-im-bored-looks-really-lazy

I have a hankering for despair and I didn't feel like doing my other stories, so I did a quick little one-shot based on this comic! I hope you liked it! Stick around to read more Undertale stories, which will hopefully be less despairing and sad in the future! ((btw if you want to see it quicker, please leave reviews/faves! okay bye! thank you again for reading this story and this note!))


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